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The Context & Problem

This article discusses the context and problems associated with marine programs collecting digital SEG-Y data. It explores the implementation of the JPEG2000 framework by the Geological Survey of Canada to encode, archive, interpret, and disseminate digital SEG-Y data. The article also explains the features and benefits of JPEG2000 as a file format and outlines the processing framework for SEG-Y to JPEG2000 conversion. Ongoing and future research efforts are highlighted, along with the availability of tools and schemas developed by the Geological Survey of Canada for data dissemination.

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The Context & Problem

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  1. Storage and Dissemination of SEGY Data in JPEG2000 Format Bob CourtneyGeological Survey of Canada (Atlantic)Bob.courtney@nrcan.gc.ca

  2. The Context & Problems The Context & Problem • Marine program collecting digital SEGY data since early 90’s • Scientists use printed field records in preference to digital products • New digital systems (e.g., 3.5 khz chirp on multibeam vessels) strictly digital. • Digital processing issues – data size ( > 1 TB/yr) , comparison to gold-standard printed records, time vs return • Discovery and Dissemination problems – cost of copying analog records, record degradation, size of digital SEGY archives • Database population and update issues – no validation of digital data

  3. GSC Implementation of JPEG2000 • GSC has implemented the JPEG2000 framework to consolidate, encode, archive, interpret and disseminate digital SEGY data. • Experience suggests between 10:1 to 40:1 compression effective • Approach applied to seismic, sidescan, and sounder data. Will (?) be extended to image trace data of multibeam sounders (water column imaging), other gridded data sets. • All ancillary data encoded via XML schemas  metadata harvesting for database during normal processing (carrot vs stick approach)

  4. What is JPEG2000 ?JPEG2000 is definitely not JPEG • Open file standard ISO/IEC 15444-1:2000 • Wavelet based, multiresolution representation • Up to 38 bit signed data – not just images • Up to 16,000 planes/channels • Entropy-based (MQ) bit-plane encoding (save 20 bits instead of 32, white space costs almost nothing) • Lossless/lossy encoding - harmonic distortion for lossy compression • Flexible file format –XML-aware, UUID defined boxes • Random access to ROI, transcoding, quality layers,etc • Internet ready : JPIP => low bandwidth optimized • Industry support: e.g., Lizardtech, Adobe Photoshop

  5. SEGY  JPEG2000Processing Framework JPEG2000 Viewers GIS Tape Encode Interpret Harvest Archive DVD Register Convert QC Internet Scan

  6. HarvestDemultiplex and Combine File 1 File 2 File n-1 Demultiplex Combine Channels Concatenate Big SEGY >200,000 pings 2 GB File n

  7. HarvestDemultiplex and Combine • Reduce number of files => 1 file/day rather than 50 • Database-linked nomenclature • Composite channel files; sidescan, 2 channel high res • Self descriptive file names • Expedition_datatype_instrument_xdcr_starttime_endtime • 2007006_SEISMIC_KNUDSON_3.5khz_132_0007_to_132_1217.sgy

  8. EncodeSEGY  SGYJP2 SEGY.xsd XML to Database GZIP XML SEGY headers Summary data 1:1 10:1 Filter Signal Cond. Outliers Bipolar Envelope Half-wave SEGY SGYJP2 JPEG2000 Compression Engine 10:1 - 40:1 Waveform Data • zero padding trace delays • lossless or lossy • keep only significant bit-depth • choose reduced bit-depth scaled to highest amplitude;

  9. EncodeSEGY  SGYJP2

  10. EncodeSEGY  SGYJP2

  11. EncodeSEGY  SGYJP2

  12. EncodeSEGY  SGYJP2 Sample from 3.5 khz Knudsen – Creed St.Lawrence Estuary 69333 traces; 13333 samples/tr ; 12 hr data; 10:1 compression Lizardtech IE plugin

  13. EncodeSEGY  SGYJP2 Signal amplitudes (in this case; envelope) encoded in file; Anti-aliasing at all zoom levels

  14. EncodeSEGY  SGYJP2 50:1 / 0.3 bpp 10:1 1.6 bpp Comparison => 10:1 to 50:1 compression

  15. EncodeSEGY  SGYJP2 Sidescan trace encoding; equally effective for MBES

  16. InterpretSGYJP2 horizons.xsd XML to Database XML Horizons View & Interpret SGYJP2 GZIP XML Markers SGYJP2 XML Sections Shapefiles GIS Automation

  17. InterpretSGYJP2

  18. InterpretSGYJP2

  19. Ongoing EffortsSGYJP2 • Shapefiles and ESRI automation • Google Earth KMZ • Drivers for Klein digital formats • GSF, XTF encoding ( XML schemas)

  20. Research EffortsSGYJP2 • Multiplane data => MBES; multichannel seismic • Wavelet transforms – custom based, KLT? • Web services => extend/adapt JPIP • Multiscale methods of data cleaning, characterization • Bathymetry gridding => 1m, 2m,4m =>multiscale • Rate versus distortion =>how much accuracy do you need? 1% , 0.1%, etc

  21. SoftwareSGYJP2 • Tools and schemas developed to disseminate GSC data • Tools and schemas are free • Single user, no distribute (need to measure impact) • Email request to bob.courtney@nrcan.gc.ca • No support – we have limited capacity • Welcome research partnerships to extend and continue efforts

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